Maximum entropy production far from equilibrium: The example of strong shock waves

The neglect of either mass, momentum, or energy conservation leaves one degree of freedom in the determination of the steady state behind stationary shock waves, the entropy production rate in the shock front becoming a function of this. In all three cases this function has an absolute maximum that is approached by the entropy production rate of real shock waves for a Mach number M close to 6 in the first case and asymptotically approached for M-->∞ in the last two cases. These results are shown to hold true also when the shock waves are treated relativistically. The example of shock waves demonstrates that some systems far from equilibrium may be characterized by maximum entropy production similarly as certain systems close to equilibrium are characterized by minimum entropy production.